LTGS from expanding/shrinking clays such as launa in Spain

[esbjornaneer]

Happy New Year everybody!
Time for more questions after observations when making a test sample this morning.
The mix I have made is 12g clay/12g NaOH binder with 1g kitchen paper & 97g clay (aggregate). That means 20%(1/1)binder with 1%fibre.
I had trouble dissolving the NaOH... so kept adding water. I gave up at 14ml as there were still 4-6 grains of NaOH and the water no longer fizzed when adding the last ml. I instead fished them out with my stirring utensil. It was difficult to know if adding more water created heat. I used the laser thermometer but parts of the inner/mixing pan that were clean metal were way cooler than the mix, and the temp of the mix went down each time inbetween adding more water. The water I added was simmering water from the water-bath pan, 1ml at the time.
I would say that the consistency that I had was more like cream than a paste.
Should I have stopped adding water before it stopped fizzing to keep the lye concentration up? Or is the fact that it fizzes the touch-stone that more water can be added? When the last ml was added some drops were placed on the crystals and nothing happened while the drops that were added to the mix still gave a small fizz. Is it possible that some of the crystals did not dissolve because of having been exposed to indoor air since 23rd Dec?

I 'dissolved' the kitchen paper in 12ml water from the water-bath pan, but it only seemed to get mushy rather than dissolve to fibres. Is that suffuciently dissolved?

I had no clue how much water would be needed for the full mix so did not follow instructions of adding water to binder then binder to aggregate. Instead I added fibres+the water wetting them to the binder. Then I added some of the dry clay/aggregate to the binder+fibre to get it to a consistency where I could get it all out of the mixing pan into a plastic container it would be easier to get it all out of as I don't have a spatula. I then added the rest of the dry clay aggregate to the binder mix. I added 24ml of water, in stages, to the wetter part of that mix in total to incorporate all the clay. The mix was the consistency of creamed butter and sugar for a cake, so quite stiff but still spreadable.
How much of a difference does it make what order I add binder, water & clay/aggregate together? Can this be a reason if this sample does not work out?
Will the total water need stay about the same (~50ml) for the same weight samples that increases fibre and reduce aggregate while the binder stays the same? You said some of the clay can be held back to adjust the mix. Can that be done by adding water at the end instead?

My plan, as hinted at in my first post, is to get this information into a 'recipe' with all information as clearly laid out as possible but I have to get it right before I can post it.

[Deleted]

Dissolving with respect to paper means just that it disintegrates into individual fibers.

Fibers should not be added to the binder as the concentrated lye will weaken them or even destroy them completely.
In any case some of the lye will be used up and not longer be available for the main purpose.

Adding the binder to the water guarantees the best possible distribution throughout the whole mixture.
However this approach requires to make prior tests with small amounts of material to find out the required amount of water.

With this approach the order of the other components is not very important.
If any accelerator is used it has to be added as the last incredient.

[esbjornaneer]

I know Karl that you have said that I should mix clay with NaOH dry then add minimum water to dissolve the NaOH to make the binder.
So to make an experiment I dissolved 12g NaOH into just water in decreasing amounts: 9, 6, 3ml(1ml=1g).
They all seemed to dissolve to about the same grainyness with the pots in a hot water bath.
When I added 12g of clay to each after the lye was as liquid as it went all seemed to get more liquid. But the stiffest ofcoarse was the 3ml sample.
Then I thought that chemistry calculations should help me...
I understand that each NaOH uses one H2O to reach liquid form.
To get the proportions right I am going to the molecular weights: NaOH=40g/mol; H2O=18g/mol
I use 12g NaOH in my test samples so I should need x gH2O= 18*12/40=5.4g

You how are more experienced at mathematical chemical calculations point me right please.

[Deleted]

Well, it depends a lot on the kind of clay.
For some a binder may be possible with just slightly more than 20% of water.
Expansive clays require a lot more, likely more than 40% or even 100%.
That's why I have said that it may be difficult to make a binder from such clays.

[esbjornaneer]

Sorry Karl, these percentages are refering to what? Still the dry weight of the mix?

[Deleted]

Yes, dry weight as always.

[esbjornaneer]

I have 'condensed' Karls advice into the recipe below.
I have not at this point managed to make a successfull geopolymer with this recipe and launa! But Karl pointed out that even thoug some launa samples would work with this recipe others would not. Due to this complication I am moving on to other clay/mineral sources for future experiments.

Thank you for any comments on where I (may) have misinterpreted Karl's advice previously in the thread(s).


LTGS Expansive clay recipe

Equipment needed:

Double boiler or equivalent.
Cooker top
Scales
Small spoon
Stirring implement
Bowls for measured ingredients

Ingredients (as % in dry weight of total mix):


20% Binder:
10% Caustic Soda
10% Expansive clay
+ minimum water

Fibre:
3%-1% kitchen/toilet paper

Aggregate:
77%-79% Expansive clay

40-100% water to desired consistency
--------------------------------------

30% Binder:
15% Caustic Soda
15% Expansive clay
+ minimum water

Fibre:
3%-1% kitchen/toilet paper

Aggregate:
67%-69% Expansive clay

40-100% water to desired consistency
---------------------------------------

40% Binder:
20% Caustic Soda
20% Expansive clay
+ minimum water

Fibre:
3%-1% kitchen/toilet paper

Aggregate:
57%-59% Expansive clay

40-100% water to desired consistency
---------------------------------------

Procedure

Only use very finely powdered clay, the finer the particles the greater potential for high insulation values, as well as fine particles being easier for the lye to dissolve/react with.

To make the binder:
Heat water in the bigger pan, to use as a double boiler with a smaller pan as the mixing receptacle. Check periodically during the process and make sure you do not run out of water in the bigger pan.

Put the smaller pan into the hot water and mix the dry Caustic Soda and Expansive clay in it. Handle the caustic soda and clay with care, and use proper safety precautions, as clay is a dust inhalation hazard, and the caustic soda can burn lungs, eyes, and skin.

Once thoroughly mixed add small amounts of hot water, stirring in all the water before adding any more.
Do it slowly, small amounts at a time.
You need to dissolve all the Caustic Soda crystals but with minimum water!
(The water that is initially taken up by the clay will be released in the chemical process and become available which may make it too wet lowering the lye concentration that need to be kept high.)

If possible check whether the addition of more water increases the temperature of the contents of the small pan. When more water no longer increases the temperature you have added enough.

Keep mixing until you have a thick smooth paste.

The amount of time this will take depends on the type of expansive clay you use. When the mix gets very thick water can be added in small increments again as before.

The chemical process needs water at this point, but if too much was added at an earlier stage, you will not have maintained sufficient caustic soda concentration to successfully dissolve and react with the clay particles.

At this point the mixing of the binder is complete, but it may be beneficial for the completed geopolymer to let it rest up to several hours to complete the chemical reactions desired. Only testing with your clay source will show.

Keep the binder as concentrated as possible until you are ready to mix it with aggregate and fibre. If it is too dry it will 'go off' and not be possible to use so find the balance or only mix what you intend to use.

To dissolve paper put it in hot water and stir until dissolved to fibres, put to the side for use at the end. (This water is part of the total for your mix.)

Add what will be the right quantity of warm water for your completed mix to the binder and make smooth.

(Keep an account of how much water you used and how much you added later to get this quantity more accurate with each mix you make.)

Add this to the dry aggregate and mix thoroughly.

Last add fibre, mix thoroughly, and the mix is ready to use.

It can be used in spreadable consistency onto a former/shape you desire to achieve or can be used as thick as adobe and can be pushed into a mould.

It does not need covering nor wetting after you have got it into the desired shape. Just let it dry.

If it is dried too quickly capillary forces may move the salts towards the surface which is not desired.
Once the mix is dry it can be cured at room temperature for several weeks or faster at elevated temperatures 65-100degC or higher may be needed depending on your clay.

When submerged in water for 24 hours it should hold its shape, including sharp edges/thin parts. If it falls apart it did not produce LTGS. If it retains it's shape then you have made synthetic stone LTGS Geopolymer!

[esbjornaneer]

I got a batch of 1/1 clay/NaOH binder stuck in the mixing bowl today and got this help from Karl:

Jan 26, 2018 10:48:23 GMT -8 @karl said:

Standard 1/1 binders remain watersoluble due to the extreme lye content of 50%.
I was able to dissolve all my hardened 1/1 binders with hot water.

I'm sure it will help others to

[coastalrocketeer]

Jan 2, 2018 11:40:02 GMT -8 esbjornaneer said:

Sorry Karl, these percentages are refering to what? Still the dry weight of the mix?

I think the portion of the mix (binder and/or aggregate) that has such high water demand, like the bentonite I'm currently experimenting with.

5:1 water demand, to get it to the mayo consistency with just the clay... but quite a bit less thickening occurs with the same clay:water ratio when added to my alkaline zeolite binder.

Not sure why. Karl may be able to shed light on that.

[esbjornaneer]

With regards to the "minimum water" amount for the binder this might be of interest to you coastalrocketeer :

Jan 26, 2018 7:10:53 GMT -8 @karl said:

A binder requires less water than the mineral alone.
To get an idea you can make a thick paste from the clay and then add the dry lye and stirr.
The mixture usually becomes much more liquid before it starts to thicken.

How long it takes depends on the clays particle size and composition.
While very small particles are easier to attack they require more water which lowers the concentration.
The minerals in the particles can be ordered or unordered.
Unordered minerals are more prone to attack.
I have got a red clay with high iron content and 6% potassium oxide, of which a binder gets hard within a few minutes.
Binders made from white high alumina clays like kaolin do thicken but usually do not harden.

I did such a mix with 12g fire clay, 3g water & 12g NaOH, within an hour of the above message from Karl. There were still NaOH grains/pellets in the mix when I had mixed it fully! Then a few hours later (1/2/3 I can't remember) it had all gone hard and I had to stab it with my stirring/chop-stick to work it into a paste again, still with NaOH grains/pellets un-dissolved. I kept having to stir/mash it every few hours as it kept going hard-ish (this was directly following geting a binder stuck to the bottom of a pan ). Next morning, 27th, there were still grains to mash, but the paste was coming together and smoothing out. I stirred again in the evening, 27th, then morning and evening 28th. Now in the morning of the 29th it is really quite liquid and instead of staying, as a mound, in a corner of the container it wants to run and cover the bottom of the container.
This mix was done in a cool 16-18degC kitchen with at times high humidity from steaming pans.
@karl how likely is it that the binder has extracted moisture from the air? At what point would the binder have been ready for mixing with aggregate?

I have no idea if this is a guide method for water quantity when working with zeolite/bentonite.

[Deleted]

One should use a glass not a metal container to keep the chemical heat concentrated.
It is not very likely that the binder has drawn water from air.
The binder is usable once it has cooled down, however a longer rest may improve it.
All depends also on the kind of clay.

[esbjornaneer]

Thank you Karl, I have been intending to ask you what would be ideal equipment to work with/in and here is the answer.

As for cooling down... The mix was going down in temp within 5-10 minutes, way before all the NaOH was dissolved.

[Deleted]

Jan 29, 2018 10:08:47 GMT -8 esbjornaneer said:

As for cooling down... The mix was going down in temp within 5-10 minutes, way before all the NaOH was dissolved.

Never happened to me.

[esbjornaneer]

But I take it that both has to have occured for the mix to be ready: NaOH dissolved and cooled down.

I did not mention that I never heated this binder mix. It did heat up to a nice warm temp on my hand through the side of the old butter container I used for mixing it in.

[Deleted]

The dissolving lye delivers quite a lot heat
and one can use hot water for the mix.